"It's an explosion!" says Stephen Schutz, the man behind one of the leading greeting-card Web sites. Ever since opening his Web site for Halloween cards in the fall, Mr. Schutz's card company has seen use of the site double every 10 days. "We'll probably send 10 million cards this Christmas over the Net," he says. That is more cards than he'll sell on paper.

Blue Mountain Arts, based in Boulder, Colo., offers some of the most sophisticated on-line greetings. But it is not alone. Everyone - from the smallest card companies to industry giant American Greetings Corp. is dreaming of a cyber Christmas. Even the government of Prince Edward Island is offering Web-based Yuletide greetings, complete with photographs of provincial landscapes that users can personalize with their own messages.

With a few exceptions, most notably American Greetings' $1.95 charge for sending cyberspace greetings, most on-line Christmas cards are free. This represents a challenge for the industry. As its members invest increasing amounts of cash in their Internet service, they're eager to find a way to pay for it.

Even Schutz, who wants to keep his on-line service free as long as possible, has had to expand. From one Internet computer two months ago, he now has seven running to keep up with the demand that, at times, has crashed his system. To pay for the service, he's considering adding special features that only paying customers could add to their cards.

As popular as Internet cards are becoming, no one is predicting they'll take over the $6 billion greeting-card business. "The industry feels pretty secure in the traditional kinds of cards that people purchase," says Marianne McDermott, executive vice president for the Greeting Card Association, based in Washington, D.C. Christmas cards are by far the industry's most popular item. This year Americans, mostly women, are expected to purchase nearly 2.7 billion of them.

Cyberspace "opens to us a whole new consumer group," adds Ms. Fewell of Hallmark. If the industry can get on-line males to send cyber-greetings, then perhaps it can lure them in to buy traditional cards.